I assume that this isn't on your phone, because otherwise you can just find out yourself: pull the notifications down if it's a notification - as most of these questions are - or if it's on the desktop just touch the icon and see what happens. The icons look like notifications, but there seems to be a lot of space above them and you say "app icon", which is why I wonder whether they are desktop app launcher icons? If they are then someone has used a theme or icon pack to change their appearance, which makes definite identification harder. And as the image is low res zooming doesn't help get a better look at it.
So, with those caveats, my first thought is that it looks like a mountain or maybe a flame. If it's a flame then it's the wrong shape for Tinder (which I mention because most of these questions are from people with relationship insecurities and are really asking "is this a dating app?" - apologies if that isn't you!). The thing it reminds me of most is the Paramount movie studio logo (mountain in front of the sky, all in a circle) - it's not an exact match, but if it's been simplified into a notification (or something that looks like one) then maybe?
To be honest though, there are so many apps (literally millions) that your best bet is probably to ask the phone's owner (unless that is you).